Add GHA

[hfrick]

from https://github.com/cran-task-views/ctv/tree/main/validate-ctv

via https://github.com/cran-task-views/ctv/blob/main/Maintenance.md#task-view-updates

@zeileis I ran into this when trying to open the PR directly from my IDE (Positron with the GH extension). Before I dive into details, are you generally open to changing access permissions here?

Although you appear to have the correct authorization credentials, the cran-task-views organization has enabled OAuth App access restrictions, meaning that data access to third-parties is limited. For more information on these restrictions, including how to enable this app, visit https://docs.github.com/articles/restricting-access-to-your-organization-s-data/

[zeileis]

Hannah @hfrick, I'm sorry I don't know what this means exactly. To me your PR looks reasonable. Maybe Nathalie @tuxette knows better what the problem might be here.

In any case, I don't recall that we discussed OAuth App access restrictions explicitly. I guess this never came up so far.